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Indian Journal of Ophthalmology Jan 2019A 75-year-old male with a right eye history of chronic dry eye syndrome, glaucoma status post tube shunt, and Fuchs dystrophy status post Descemet stripping endothelial...
A 75-year-old male with a right eye history of chronic dry eye syndrome, glaucoma status post tube shunt, and Fuchs dystrophy status post Descemet stripping endothelial keratoplasty followed by penetrating keratoplasty (PKP) presented with a 2.7 × 4.2 mm corneal ulcer, culture positive for Shewanella algae and Klebsiella oxytoca. A topical antibiotic regimen of gentamicin 14 mg/mL and vancomycin 50 mg/mL was administered according to culture sensitivities. There was concurrent use of loteprednol 0.5% (Lotemax Gel, Bausch and Lomb, Rochester, NY, USA) and later addition of erythromycin 0.5% ointment. The corneal ulcer improved with antibiotic therapy but was complicated by poor patient follow-up. Descemetocele formation prompted PKP in the right eye. The graft was successful and visual acuity improved from a low of light perception to maximum of 20/200 Snellen.
Topics: Aged; Anti-Bacterial Agents; Cornea; Corneal Ulcer; Eye Infections, Bacterial; Gram-Negative Bacterial Infections; Humans; Male; Shewanella
PubMed: 30574928
DOI: 10.4103/ijo.IJO_617_18 -
Clinical Microbiology and Infection :... May 2005The occurrence of the two Shewanella species found in clinical specimens, Shewanella algae and Shewanella putrefaciens, correlates with the temperature and salinity of... (Comparative Study)
Comparative Study Review
The occurrence of the two Shewanella species found in clinical specimens, Shewanella algae and Shewanella putrefaciens, correlates with the temperature and salinity of seawater. This means that Shewanella infections occur in warm climates or during especially warm summers in temperate climates. The infections described most commonly involve ears, skin and soft tissue, with or without bacteraemia. Primary bacteraemia with a fulminant course is also seen in immunocompromised patients. Important differential characteristics between the two species include the ability of S. algae to produce mucoid colonies with beta-haemolysis on sheep blood agar, to grow at 42 degrees C and in NaCl 6% w/v, and to reduce nitrite, and an inability to produce acid from maltose, all of which are in contrast to the characteristics of S. putrefaciens. Automated identification systems fail to differentiate between S. algae and S. putrefaciens, as S. algae is not included in the databases of these systems. Presumably for this reason, most Shewanella infections reported during recent years have been attributed to S. putrefaciens. However, when extensive phenotypic characterisation is performed, most human infections are seen to be caused by S. algae. As the two species seem to have different pathogenic potential for humans, correct identification is important, and this is possible in routine clinical microbiology laboratories.
Topics: Animals; Anti-Bacterial Agents; Ear Diseases; Gram-Negative Bacterial Infections; Humans; Microbial Sensitivity Tests; Phenotype; Seawater; Shewanella; Shewanella putrefaciens; Skin Diseases, Bacterial; Temperature
PubMed: 15819859
DOI: 10.1111/j.1469-0691.2005.01108.x -
Microbial Biotechnology May 2021Bacterial colony morphology can reflect different physiological stages such as virulence or biofilm formation. In this work we used transposon mutagenesis to identify...
Bacterial colony morphology can reflect different physiological stages such as virulence or biofilm formation. In this work we used transposon mutagenesis to identify genes that alter colony morphology and cause differential Congo Red (CR) and Brilliant Blue G (BBG) binding in Shewanella algae, a marine indigenous bacterium and occasional human pathogen. Microscopic analysis of colonies formed by the wild-type strain S. algae CECT 5071 and three transposon integration mutants representing the diversity of colony morphotypes showed production of biofilm extracellular polymeric substances (EPS) and distinctive morphological alterations. Electrophoretic and chemical analyses of extracted EPS showed differential patterns between strains, although the targets of CR and BBG binding remain to be identified. Galactose and galactosamine were the preponderant sugars in the colony biofilm EPS of S. algae. Surface-associated biofilm formation of transposon integration mutants was not directly correlated with a distinct colony morphotype. The hybrid sensor histidine kinase BarA abrogated surface-associated biofilm formation. Ectopic expression of the kinase and mutants in the phosphorelay cascade partially recovered biofilm formation. Altogether, this work provides the basic analysis to subsequently address the complex and intertwined networks regulating colony morphology and biofilm formation in this poorly understood species.
Topics: Biofilms; Humans; Mutagenesis; Shewanella; Virulence
PubMed: 33764668
DOI: 10.1111/1751-7915.13788 -
MSystems Apr 2022spp. play important ecological and biogeochemical roles, due in part to their versatile metabolism and swift integration of stimuli. While spp. are primarily...
Comparative Genomics of Cyclic di-GMP Metabolism and Chemosensory Pathways in Shewanella algae Strains: Novel Bacterial Sensory Domains and Functional Insights into Lifestyle Regulation.
spp. play important ecological and biogeochemical roles, due in part to their versatile metabolism and swift integration of stimuli. While spp. are primarily considered environmental microbes, Shewanella algae is increasingly recognized as an occasional human pathogen. S. algae shares the broad metabolic and respiratory repertoire of spp. and thrives in similar ecological niches. In S. algae, nitrate and dimethyl sulfoxide (DMSO) respiration promote biofilm formation strain specifically, with potential implication of taxis and cyclic diguanosine monophosphate (c-di-GMP) signaling. Signal transduction systems in S. algae have not been investigated. To fill these knowledge gaps, we provide here an inventory of the c-di-GMP turnover proteome and chemosensory networks of the type strain S. algae CECT 5071 and compare them with those of 41 whole-genome-sequenced clinical and environmental S. algae isolates. Besides comparative analysis of genetic content and identification of laterally transferred genes, the occurrence and topology of c-di-GMP turnover proteins and chemoreceptors were analyzed. We found S. algae strains to encode 61 to 67 c-di-GMP turnover proteins and 28 to 31 chemoreceptors, placing S. algae near the top in terms of these signaling capacities per Mbp of genome. Most c-di-GMP turnover proteins were predicted to be catalytically active; we describe in them six novel N-terminal sensory domains that appear to control their catalytic activity. Overall, our work defines the c-di-GMP and chemosensory signal transduction pathways in S. algae, contributing to a better understanding of its ecophysiology and establishing S. algae as an auspicious model for the analysis of metabolic and signaling pathways within the genus . spp. are widespread aquatic bacteria that include the well-studied freshwater model strain Shewanella oneidensis MR-1. In contrast, the physiology of the marine and occasionally pathogenic species Shewanella algae is poorly understood. Chemosensory and c-di-GMP signal transduction systems integrate environmental stimuli to modulate gene expression, including the switch from a planktonic to sessile lifestyle and pathogenicity. Here, we systematically dissect the c-di-GMP proteome and chemosensory pathways of the type strain S. algae CECT 5071 and 41 additional S. algae isolates. We provide insights into the activity and function of these proteins, including a description of six novel sensory domains. Our work will enable future analyses of the complex, intertwined c-di-GMP metabolism and chemotaxis networks of S. algae and their ecophysiological role.
Topics: Humans; Bacterial Proteins; Proteome; Biofilms; Shewanella; Genomics
PubMed: 35311563
DOI: 10.1128/msystems.01518-21 -
Microbiology (Reading, England) Dec 2021Members of are ubiquitous in aquatic environments, some of which have been implicated in human infections. The progenitors of antibiotic resistance genes with clinical...
Members of are ubiquitous in aquatic environments, some of which have been implicated in human infections. The progenitors of antibiotic resistance genes with clinical relevance, such as genes, have been identified in code for a pentapeptide repeat protein that protects type II topoisomerases, decreasing susceptibility to quinolones and fluoroquinolones. In this study, 248 genomes of 49 species were analysed as well as 33 environmental isolates belonging to 10 species. The presence of the gene was detected in 22.9% of the genomes and 15.2% of the isolates. The gene was more often detected in , but was also detected in , , and . The identified genes encoded the previously described variants QnrA3 (in 22 genomes of one species), QnrA2 (eight genomes and three species), QnrA1 (six genomes and two species), QnrA7 (five genomes and two species), QnrA10 (two genomes of one species) and QnrA4 (one genome). In addition, 11 novel variants with 3 to 7 amino acid substitutions were identified (in 13 genomes and one environmental isolate). The presence of this gene appears to be species-specific although within some species several variants were detected. The study presents a previously unknown diversity of in , highlighting the role of this genus as progenitor and reservoir of these genes. Further studies are needed to determine the phenotypes conferred by the new variants and the mechanisms that may mediate the transfer of these genes to new hosts.
Topics: Anti-Bacterial Agents; Drug Resistance, Bacterial; Quinolones; Shewanella
PubMed: 34914577
DOI: 10.1099/mic.0.001118 -
Access Microbiology 2020Macro-algae are a good source of agar oligosaccharides, which can be obtained through bacterial enzymatic hydrolysis. The agarase enzyme secreted by the micro-organisms...
Macro-algae are a good source of agar oligosaccharides, which can be obtained through bacterial enzymatic hydrolysis. The agarase enzyme secreted by the micro-organisms cleaves the cell wall of the algae and releases agar oligosaccharides as degradation products with various applications. Agarolytic bacteria were isolated from the marine algae sp., and sp., and studied for their agar-degrading properties. Among the 70 isolates, 2 isolates (A13 and Sg8) showed agarase activity in assays. The maximum agarolytic index was recorded in the isolate Sg8 (3.75 mm and 4.29 µg ml agarase activity), followed by the isolate A13 (2.53 mm and 2.6 µg ml agarase activity). Optimum agarase production of isolate Sg8 was observed at pH7 and at a temperature of 25 °C in 24-48 h, whereas for isolate A13 the optimum production was at pH7 and at a temperature of 37 °C in 48 h. The identities of the agarolytic isolates (Sg8 and A13) were confirmed based on microscopy, morphological, biochemical and molecular analysis as [National Center for Biotechnology Information (NCBI) GenBank accession number MK121204.1] and [NCBI GenBank accession number MK825484.1], respectively.
PubMed: 33294773
DOI: 10.1099/acmi.0.000170 -
Frontiers in Chemistry 2021Nanoscale materials have recently gained wide attention due to their potential to revolutionize many technologies and industrial sectors, including information... (Review)
Review
Nanoscale materials have recently gained wide attention due to their potential to revolutionize many technologies and industrial sectors, including information technology, homeland security, transportation, energy, food safety, environmental science, catalysis, photonics and medicine. Among various nanoparticles, platinum nanoparticles (PtNPs) are widely used for biomedical applications, including imaging, implants, photothermal therapy and drug delivery. Indeed, PtNPs possesses intrinsic antimicrobial, antioxidant, and anticancer properties. Also, due to their remarkable catalytic activity, they are able to reduce the intracellular reactive oxygen species (ROS) levels and impair the downstream pathways leading to inflammation. Various approaches, including both physical and chemical methods, are currently employed for synthesis of PtNPs. However, the use of hazardous reaction conditions and toxic chemicals in these processes poses a potential threat to the environment and severely compromise the biocompatibility of the nanoparticles. Hereby, increasing need for exploitation of novel routes for synthesis of PtNPs has led to development of biological fabrication using microbes, specifically bacteria. Herein, we present a most comprehensive report on biogenesis of PtNPs by several bacteria like , etc. An overview of the underlying mechanisms of both enzymatic and non-enzymatic methods of synthesis is included. Moreover, this review highlights the scope of developing optimized process to control the physicochemical properties, such as the nanoparticle surface chemistry, charge, size and shape, which, in turn, may affect their nanotoxicity and response at the biointerface for nanomedicine applications.
PubMed: 33763405
DOI: 10.3389/fchem.2021.624344 -
Microbial Genomics Feb 2022is widely distributed in marine and freshwater habitats, and has been proved to be an emerging marine zoonotic and human pathogen. However, the genomic characteristics...
is widely distributed in marine and freshwater habitats, and has been proved to be an emerging marine zoonotic and human pathogen. However, the genomic characteristics and pathogenicity of are unclear. Here, the whole-genome features of 55 . strains isolated from different sources were described. Pan-genome analysis yielded 2863 (19.4 %) genes shared among all strains. Functional annotation of the core genome showed that the main functions are focused on basic lifestyle such as metabolism and energy production. Meanwhile, the phylogenetic tree of the single nucleotide polymorphisms (SNPs) of core genome divided the 55 strains into three clades, with the majority of strains from China falling into the first two clades. As for the accessory genome, 167 genomic islands (GIs) and 65 phage-related elements were detected. The CRISPR-Cas system with a high degree of confidence was predicted in 23 strains. The GIs carried a suite of virulence genes and mobile genetic elements, while prophages contained several transposases and integrases. Horizontal genes transfer based on homology analysis indicated that these GIs and prophages were parts of major drivers for the evolution and the environmental adaptation of . In addition, a rich putative virulence-associated gene pool was found. Eight classes of antibiotic-associated resistance genes were detected, and the carriage rate of β-lactam resistance genes was 100 %. In conclusion, exhibits a high intra-species diversity in the aspects of population structure, virulence-associated genes and potential drug resistance, which is helpful for its evolution in pathogenesis and environmental adaptability.
Topics: Adaptation, Biological; Anti-Bacterial Agents; CRISPR-Cas Systems; China; Drug Resistance, Bacterial; Genetic Variation; Genome, Bacterial; Genomic Islands; Genomics; Humans; Microbial Sensitivity Tests; Phylogeny; Prophages; Shewanella; Species Specificity; Virulence
PubMed: 35143386
DOI: 10.1099/mgen.0.000786 -
BMC Microbiology Nov 2020Infections caused by Shewanella spp. have been increasingly reported worldwide. The advances in genomic sciences have enabled better understanding about the taxonomy and...
BACKGROUND
Infections caused by Shewanella spp. have been increasingly reported worldwide. The advances in genomic sciences have enabled better understanding about the taxonomy and epidemiology of this agent. However, the scarcity of DNA sequencing data is still an obstacle for understanding the genus and its association with infections in humans and animals.
RESULTS
In this study, we report the first isolation and whole-genome sequencing of a Shewanella algae strain from a swine farm in Brazil using the boot sock method, as well as the resistance profile of this strain to antimicrobials. The isolate was first identified as Shewanella putrefaciens, but after whole-genome sequencing it showed greater similarity with Shewanella algae. The strain showed resistance to 46.7% of the antimicrobials tested, and 26 resistance genes were identified in the genome.
CONCLUSIONS
This report supports research made with Shewanella spp. and gives a step forward for understanding its taxonomy and epidemiology. It also highlights the risk of emerging pathogens with high resistance to antimicrobial formulas that are important to public health.
Topics: Animals; Anti-Bacterial Agents; Brazil; DNA, Bacterial; Drug Resistance, Multiple, Bacterial; Environmental Microbiology; Farms; Genome, Bacterial; Microbial Sensitivity Tests; Phylogeny; RNA, Ribosomal, 16S; Shewanella; Swine; Virulence Factors
PubMed: 33234140
DOI: 10.1186/s12866-020-02040-x -
Life (Basel, Switzerland) Apr 2021bites cause severe soft tissue injury and are prone to wound infections. The pathogens of bite-wound infections are highly variable in different geographical regions....
bites cause severe soft tissue injury and are prone to wound infections. The pathogens of bite-wound infections are highly variable in different geographical regions. Here, we report the first coinfection with and from a bite wound with resistome analysis using whole genome sequencing.
PubMed: 33920102
DOI: 10.3390/life11040329